but the physical laws of sound are universal. at the root of all sound is vibration. [bell tolling] not only the root of all music is vibration, but in some sense, perhaps, the root of everything is vibration. everything is moving all the time. the earth is moving. the sun is moving. on the earth, the waves are beating against the shore. everything which is, is vibration. in order to have a sound, you need a physical object which vibrates, whether it's a cello or a speaker in a radio, you need a medium to carry that vibration. typically, it's air, and finally we need an ear, an ear drum, and a brain to turn it into something that's meaningful to a human being. [flute plays] the simplest sort of sound is called a sine wave, and i can display that sound on an oscilloscope. of course in nature, nothing is so simple as that. there isn't just one sine wave happening at one moment. actually, there are many sine waves all adding and subtracting. when you listen to a sound, when you listen to a musical note, you hear several things. [flute music continues] you hear the basic